How Are Oxygen Sensors Numbered in an 1998 F-150 Pickup Truck?

Ford has been producing the F-150 1/2-ton pickup since 1975, when it was introduced as a heavy-duty 1/2-ton and produced alongside the F-100 1/2-ton pickup. Ford dropped the F-100 from its lineup in 1983. Ford equipped the 1998 F-150 with a 4.2-liter V-6 base engine or optional 4.6- or 5.4-liter V-8s. The 1998 F-150 has two three-way catalytic converters and four oxygen sensors two before and two after each converter referred to as upstream and downstream." Each sensor has a position number assigned to it to identify its location.

Instructions

1

Park the F-150 on a level, paved surface and set the parking brake. If you are going to remove any of the sensors, it is a good idea to have the engine slightly warm, as this will make the sensor easier to remove. Be very careful working around warm engine parts.

2

Raise the front of the F-150 with a jack and support with jack stands. Move under the F-150 and identify the sensors as follows driver side upstream is HO2S-21, driver side downstream is HO2S-22, passenger side upstream is HO2S-11, passenger side downstream is HO2S-12.

3

Remove any sensor by pushing down on the connector tab and unplugging the sensor. The lead that runs to the sensor is part of the sensor. Use a ratchet and oxygen sensor socket to remove the sensor. The socket has a notch in it that allows you to fit the socket over the lead.

4

Thread a new sensor into the exhaust pipe and use a torque wrench and the sensor socket to torque the sensor to between 26 and 34 foot-pounds. All sensors are replaced in the same manner. If you are installing the old sensor, be sure to apply a little anti-seize compound to the threads. New sensors come with it pre-applied.

5

Plug in the electrical connector. Make sure the tab locks into place or the connector may come loose. Raise the front of the F-150, remove the jack stands and lower it to the ground.